Can low-fusing glass application affect the marginal misfit and bond strength of Y-TZP crowns?

Abstract To evaluate the effect of different surface treatments on the marginal misfit and retentive strength between Y-TZP crowns and an epoxy resin. Forty (40) epoxy resin (G10) abutments (height: 5mm, conicity: 60, finish line: large chamfer) with equal dimensions were milled and included in polyurethane to simulate the periodontal ligament. Next, 40 Y-TZP crowns (thickness: 1mm) were milled (Cerec in Lab) and randomly divided into four groups (n=10) according to the surface treatment: GS(glaze spray), GP(glaze powder/liquid), P(zirconia primer) and RS(tribochemical silica coating). The conditioned surfaces were cemented with dual self-adhesive cement, light cured and submitted to thermomechanical cycling (2x106, 100N, 4Hz, 5°/55°C). Marginal misfit was analyzed by a stereomicroscope and SEM. Retentive strength test was performed (1mm/min) until crown debonding. Glaze layer thickness was also performed to GS and GP groups. Marginal misfit data were analyzed by Kruskal Wallis and Dunn tests; one-way ANOVA and Tukey (5%) analyzed the tensile strength data. The marginal misfit of the GS (48.6±19.9μm) and GP (65.4±42.5μm) were statistically lower than the RS (96±62.9μm) and P (156±113.3μm) (p=0.001). The retentive strength of the GP (470.5±104.1N) and GS (416.8±170.2N) were similar to the P (342.1±109.7N), but statistically higher than those of the RS (208.9±110N). The GS and GP glaze layer was 11.64μm and 9.73μm respectively. Thus, glaze application promoted lower marginal discrepancy and higher retentive strength values than conventional techniques.

摘要 本研究旨在评估不同表面处理方式对Y-TZP冠与环氧树脂之间边缘密合性偏差以及固位强度的影响。本研究制备了40个尺寸一致的环氧树脂（G10）基台（高度5mm，锥度60°，肩台为大斜面肩台），并将其包埋于聚氨酯材料中以模拟牙周膜。随后，制备40个厚度为1mm的Y-TZP冠，通过Cerec in Lab系统研磨，并依据表面处理方式随机分为4组（每组n=10）：GS组（釉质喷涂法）、GP组（釉质粉液法）、P组（氧化锆底涂剂处理组）及RS组（摩擦化学硅涂层（tribochemical silica coating））。经表面处理后的冠面与基台采用双重自粘接树脂水门汀粘接，经光固化后进行热机械循环加载（2×10^6次循环，载荷100N，频率4Hz，温度区间5℃/55℃）。采用立体显微镜与扫描电子显微镜（SEM）对边缘密合性偏差进行检测分析。以1mm/min的加载速率进行固位强度测试，直至冠体脱落。此外，对GS组与GP组的釉层厚度进行了检测。边缘密合性偏差数据采用克鲁斯卡尔-沃利斯（Kruskal Wallis）检验与邓恩（Dunn）检验进行统计分析；抗拉强度数据则采用单因素方差分析（one-way ANOVA）与图基（Tukey）检验（显著性水平α=0.05）进行分析。统计结果显示，GS组（48.6±19.9μm）与GP组（65.4±42.5μm）的边缘密合性偏差显著低于RS组（96±62.9μm）与P组（156±113.3μm）（p=0.001）。GP组（470.5±104.1N）与GS组（416.8±170.2N）的固位强度与P组（342.1±109.7N）无显著差异，但显著高于RS组（208.9±110N）。GS组与GP组的釉层厚度分别为11.64μm与9.73μm。综上，相较于传统表面处理技术，釉质涂层处理可获得更低的边缘密合性偏差与更高的固位强度。